大流量呼吸性粉尘采样器的现场比较——增重过少的解决之道

Comparative field study on high flow rate samplers for respirable fraction-A solution to smaller collectedmasses

目的探讨以大流量采样器采样，增加滤膜粉尘颗粒负载，来解决样本增重过低，以至于达不到最低检出限（1imit of detection，LOD）的问题。方法在A和B2家造船厂，采用高流量FSP-10和常规流量FSP-2呼吸性粉尘采样器，在同一电焊作业地点平行采集呼吸性电焊烟尘。FSP-10采气流量为10L／min，FSP-2为2Umin，采样持续时间分别为3．O-4．0h和2．0-2．5h。比较分析这两种采样器所获样本的增重、粉尘浓度以及LOD的符合率。结果大流量旋风器FSP-10采集样本的粉尘增重在A和B2家船厂分别为（0．97±0．40）和（1．61±0．86）mg，明显高于常规流量FSP-2的（O．29±0．12）和（0．51±0．27）mg，差异有统计学意义（P〈0．05）。并把LOD符合率平均由26．8％（FSP-2采集时，2厂的样本合计）提高到89．7％，差异有统计学意义（X^2值=32．9085，R0．01）。大流量旋风器FSP-10与常规流量旋风器FSP-2所测呼吸性粉尘浓度比较，差异无统计学意义（P〉0．05）。常规流量旋风器FSP-2采样时间与其样本增重呈正相关关系（R^2=0．7906，y=0．0026x），若达到LOD（0．5mg），常规流量旋风器FSP-2采样时间应该≥192.3min。结论大流量旋风器FSP-10可以提高样本增重，基本上解决了LOD符合率过低的问题，而且所测粉尘浓度与常规流量旋风器FSP-2的差别不显著。

Objective Dust sample mass gain is too smaller to satisfy the limit of detection （LOD） even in most cases during dust sampling at workplaces nowdays, especially for respirable fraction. Therefore, it is aimed to solve the problem by increasing sample load with high flow rate samplers. Methods In A and B two shipyards respirable welding fume was sampled by high flow rate cyclone samplers of FSP-10 （10 L/min） for 2- 2.5 hours and normal flow rate FSP-2 （2 L/min） for 3-4 hours with a stratigy of parallele sampling at the same workpalce, in order to compare their mass gain, coincidence rate with LOD, and airborn dust concentration. Results Sample mass gain of 0.97±0.40 mg and 1.61±0.86 mg respectively in the two factories by FSP-IO was significantly higher than that of 0.29±0.12 mg and 0.51 ±0.27 mg by FSP-2 （t-test, P〈0.05 in both cases）, increasing herewith the coincidence rate with LOD from 26.8% （when sampling with FSP-2, calculated together with samples of the two factories） to 89.7%. However there was no significant difference in dust concentrations by the two different samplers, 0.53±1.88 vs 0.73±1.61 mg/m3 by FSP-2 and FSP-10 in the shipyard A and 1.14± 1.78 vs 1.01±1.63 mg/m3 in the factory B （t-test, P〉0.05 in every case）. In addtion, sample loading by FSP-2 was found to be correlated to sampling time （R^2=0.7906, y=0.O02 6x）, therefore, it has to sample for≥ 192.3 min to meet the LOD （0.5 mg） in case of normal flow rate. Conclusion By using of high flow rate cyclone FSP-10 the problem of LOD could be solved, along with increased sample mass and similar respirable dust concentration by the two samplers. Some techincal improvements of FSP-10 and increasing of LOD coincidence rate by other methods was also disscussed.